Didier Drogba will not play in Chelsea's FA Cup third-round tie against Portsmouth at Stamford Bridge on Sunday, having agreed to answer Ivory Coast's call for him to join up beforehand for the Africa Cup of Nations preparations.

André Villas-Boas, the Chelsea manager, indicated after his team's 2-1 win at Wolverhampton Wanderers on Monday, in which Drogba did not feature because of a minor foot injury, that he feared the striker would not be available against Portsmouth, although he promised the club would "try our hardest" to retain him.

The Africa Cup of Nations in Gabon and Equatorial Guinea kicks off on 21 January and the competing teams are permitted to call upon their players 14 days in advance, in other words, from Saturday. But Chelsea's Premier League rivals Manchester City and Arsenal are hopeful of keeping their Ivorian internationals for the FA Cup fixtures against Manchester United on Sunday and Leeds United on Monday, respectively, and they remain in delicate negotiations with the Ivory Coast Football Federation about that possibility.

Roberto Mancini, the Manchester City manager, has made it clear that he wants the Touré brothers, Yaya and Kolo, to be available to face Manchester United at the Etihad Stadium, and his Arsenal counterpart, Arsène Wenger, has done likewise regarding Gervinho for the Leeds tie at the Emirates.

Both might argue that their players are fully fit, having not had a winter break like some at other European clubs and, as such, they would not require the full 14 days of pre-tournament training. City also have the Carling Cup semi-final first leg at home against Liverpool next Wednesday to consider and both clubs have noted that Ivory Coast's first fixture is not until 22 January, against Sudan.

Arsenal remain in talks to finalise the loan signing of Thierry Henry from the New York Red Bulls and the deal must be signed off by midday on Friday for him to be available against Leeds. Wenger would not want to lose that race against time and also be without Gervinho.

The Tourés and Gervinho are torn between the needs of club and country, with the sensitivity of the situation exacerbated by the civil war that Ivory Coast has endured and the way that this edition of the Africa Cup of Nations has been presented as the opportunity to raise the people's spirits. Ivory Coast are the hot favourites for the title, which they last won in 1992.

Drogba's status in his homeland goes beyond that of a mere sporting icon and is quasi-presidential. Out of all Ivory Coast players, he is under the most pressure to meet the demand of the coach François Zahoui to report on time. Salomon Kalou, his Chelsea and Ivory Coast team-mate, will travel with him to the squad's pre-tournament training camp and he will also be unavailable for the Portsmouth game.

Villas-Boas and Chelsea would take a dim view if City and or Arsenal were given special dispensation to keep their Ivorian players in order to play them in the Cup. Villas-Boas wants a consistent approach to be taken by the Ivory Coast federation.

The Portsmouth tie has taken on increased significance in light of Chelsea's recent struggles and those of Villas‑Boas to impose his will on some of the dressing-room's established names. The win at Wolves was the team's first in five Premier League matches. Home form has been edgy and confidence likewise. "It's true that we've had a little crisis of results," the midfielder Juan Mata said.

Villas-Boas is without the injured Michael Essien and Mikel John Obi, Branislav Ivanovic and Danny Sturridge are doubts, Florent Malouda is ill and Alex remains in exile.